Resins and process for producing same from reaction products of hydroxy aromatic aldehydes and mercaptans



Patented Jan. 13, 1953 UNITED STATES PATENT-- o l-rice:

RESINS- AND 3 PROffElfiiilRiPRGDUGING i SAME FROM.REACTION-PRODUCTS" OE... HYDROXY AROMATIQALDEHYDES AND MERCAPTAN S No Drawing. Application June 13, 1950, Serial No. 167,911

16 elaims 1 This application is a continuation-in-part of my now abandoned co-pending application Serial Number 764,567 which wasfiled July '29, 1947.

This invention relates to a process for producing sulfur-containing resins;

An object of' this invention is to prepare a clear resin.

Another object'of this inventionis t'o'prepare a thermoplastic-resin containing sulfur.

One' specific embodiment of'this invention relates to a process for preparing a resin'which comprises reacting a hydroxy aromatic aldehyde and a merca'ptan in the presence 'of' an acidic catalyst, separating unconverted "starting ma"- terials and catalysts from the reaction product, and heatingsaidreaction product to form a resin;

Another embodiment of this invention relates to a process for preparing a resin which comprises reacting an orthohydroxy aromatic aldehyde and an alkyl mercaptan in thepresence of an acidic catalyst, separating unconverted starting materials and catalysts from the reaction product, and heating said reaction product to form a resin.

A further embodiment of this invention relates to a process for preparing-a resin which comprises reacting an orthophenolic aldehyde and drogen-chloride catalyst, separating unconverted starting materials and catalyst from the reaction product, and heating said reaction product to form a resin.

According to this process a hydroxy aromatic aldehyde reacts readily with an alkyl mercaptan in the presence of an acidic catalyst to form a hydroxy aromatic dialkylthioacetal and this reaction product is converted into a resin by heating.

The hydroxy aromatic aldehydes hydroxy phenyl aldehydes, hydroxy naphthyl aldehydes, and hydroxy aldehydes containing other aromatic nuclei. The hydroxy aromatic aldehydespreferred for use in the process are e orthohydroxy aromatic aldehydes, thesecominclude pounds being those. in which the hydroxyland aldehyde groups. are" combined with adjacent carbon atoms of the aromatic ring. Salic'ylaldehyde is an exampleiof such an ortho-substituted. hydroxy phenyl: aldehyde: Other hy droxy aromatic aldehydes are. also utiliz'able'in the process even though the hydroxy-land alde hyde groups are. not in ortho. position to one another. Thus a resinous product is obtained by the reaction .of -an. alkyl mercaptan and vanillin, also. referred to as 4-hydroxy-3-inethoxybenzaldehyde. I

Acidic catalysts suitable for promoting the process of this invention xcomprise hydrogen chloride, hydrogen bromide, phosphoric acids, particularly ortho, pyro; tri and tetra" phosphoric acids, phosphorus-pentoxide, and the like. Anhydrous hydrogen -chloride is a --particularly useful catalytic *material as it may be added readily in controlledamounts to a reaction-mixture comprising the-hydroxy aromatic aldehyde and alkyl'mercaptan'.

Mercaptans suitable for use in th'e process are represented by theformulaRS'I-I in which "R represents" a member of the group consisting of an alkyl group, an 'aryl groupgan alkaryl group, an aralkyl group; "a *cycloa-lkyl' group,ja cycloalkaryl 'groupp and an alkcyclo'alkyl group: The lower alkyl mercaptans such'a's methyl; ethyl, propylg'isopropyl; n-butyhisobutyl; sec-butyl and tertiary 'butyl; and thevarious 'amyl merc'aptans are particularly useful in '"this' process: Some of the lower boiling mercaptans including ethyl, propyl and isopropyl mercaptans are available in the form of a:mercaptan mixture."that is separated from sulfur-containing petroleum fractions by extraction with a solutionfof oaustic soda dissolved= in*'methanol.. Other suitable mercaptan compounds:of-=the class RSHJnclude thiophenol, 'thiocresol, and the like, andother compounds in which the R.group. contains a substituent as in "th'ioglycycollic acid, mercaptoethanol, and other 'mecraptoalcohols;

Thereaction of a hydroxy 'aromatic' aldehyde with a mercaptan is illustrated by the following equation which shows the condensationof sali cylaldehyde 'and an alkyl "mercaptan.

CHO CH(:SR):3

After the resultant thioacetal is freed from unconverted starting material and catalyst, as by washing and fractional distillation, the acetal is then heated to convert it into a resin. This heating is usually carried out at a temperature of from about 100 to about 350 C. and preferably at a temperature of from about 125 to about 275 C. It is sometimes advantageous to carry out this heat treatment at a subatmospheric pressure to produce a high quality resin.

This process is carried out either batchwise or in a continuous operationby mixing approximately one molecular proportion of the hydroxy aromatic aldehyde with about two molecular proportions of the mercaptans or of a mixture of mercaptans and then contacting this mixture with an acidic catalyst fora time sufficient to effect the condensation reaction to form' an arcmatic aldehyde dialkylthioacetal which is then separated from unconverted starting materials and catalysts and the purified thioacetal is then heated to form a resin. Unconvertedstarting materials recovered from the first step of the process are suitable for recycling thereto to produce an additional quantity of the thioacetal.

The resin formed by this process is useful as a coating material for paper, cloth, wood, metal, etc., or it may be mixed with fillers such as wood flour and/or other polymeric materials and molded into articles. Also some of the resins formed by this process are slightly tacky and can be used as a plasticizer for rubber and other elastomers.

The process is illustrated by the following examples which should not be misconstrued to limit unduly the broad scope of the invention.

Example I One molecular proportion of salicylaldehyde was mixed with two molecular proportions of ethyl mercaptans and anhydrous hydrogen chloride was introduced into the reaction mixture at 20 C. Reaction of the salicyl aldehyde and ethyl mercaptan took place vigorously with evolution of heat. The resultant reaction product, salicylaldehyde diethylthioacetal, was washed with water to remove hydrogen chloride, it was then dried, and subjected to distillation, at a pressure of 2 mm. of mercury. Small amounts of unconverted starting material were removed by this distillation leaving a residue which set to a clear amber resin at'a distillation still temperature of 140 to 160C. This resin is useful as a coating material and can be molded with fillers or blended with other polymeric products.

Example II 15.2 grams (0.1-. mole) of vanillin and 12.4 grams of ethyl mercaptan (0.2 mole) were dissolved in 50 cc. of diethyl ether at 20 C. and anhydrous hydrogen chloride was bubbled into the solution for about 15 seconds. Reaction occurred as evidenced by the evolution of heat and separation of water from the reaction mixture. After the reaction, the resultant mixture of reaction product and ether was washed with water to remove the hydrogen chloride, it was then dried and the ether was distilled off first at atmosphericpressure and laterat a subatmospheric pressure. The residue in the distilling flask which consisted of a condensation product of vanillin and ethyl mercaptan (mainly vanillin diethylthioacet'al) was-then heated at 200 to 250 C. for 1 hour whereupon a. resin was formed having an odor similar to that of cloves. This 4 resin which is thermoplastic is slightly soluble in acetone but nearly insoluble in other organic solvents. It is slightly tacky and can be used as plasticizer or in suitable molding compositions.

I claim as my invention:

1. A process for preparing a resin which comprises heating the reaction product formed by reacting a hydroxy aromatic aldehyde having a hydroxy group attached to a ring carbon atom and ethyl mercaptan in the presence of an acidic catalyst. said heating being at a temperature and 101 a time suhicient to resinify said reaction product.

2. A process for preparing a resin which comprises heating the reaction product formed by reactin a hydroxy aromatic aldehyde having a hydroxy group attached to a ring carbon atom and an alkyl mercaptan in the presence of an acidic catalyst.

3. A process for preparing a resin which comprises heating the reaction product formed by reacting an aromatic aldehyde having a hydroxy group attached to a ring carbon atom in ortho position to the aldehyde group and an alkyl mercaptan in the presence or an acidic catalyst.

4. A process for preparing a resin which comprises heating the reaction product iormed by reacting an orthophenolic aldehyde and an alkyl mercaptan in the presence of an acidic catalyst.

5. A process for preparing a resin which comprises heating the reaction product formed by reacting an orthophenolic aldehyde and an alkyl mercaptan in the presence of a hydrogen chloride catalyst.

6. A process for preparing a resin which comprises heating at a temperature of from about 125 C. .to about 275 C. the reaction product formed by reacting a hydroxy aromatic aldehyde having a hydroxy group attached to a ring carbon atom and a mercaptan in the presence of an acidic catalyst, said heating being for a suflicient time to resinify said reaction product.

7. A process for preparing a resin which comprises heating at a temperature of from about 125 C. to about 275 C. the reaction product formed by reacting a hydroxy aromatic aldehyde having a hydroxy group attached to a ring carbonatom and an alkyl mercaptan in the presence of an acidic catalyst.

8. A process for preparing a resin which comprises heating at a temperature of from about 125 C. to about 275 C. the reaction product formed by reacting an aromatic aldehyde having a hydroxy group attached to a ring carbon atom in ortho position to the aldehyde group and an alkyl mercaptan in the presence of an acidic catalyst.

9. A process for preparing a resin which comprises heating at a temperature of from about to about 350 C. the reaction product formed by reacting an orthophenolic aldehyde and an alkyl mercaptan in the presence of an acidic catalyst.

10. A process for producing a resin which comprises heating a hydroxy aromatic aldehyde dialkylthioacetal having a hydroxy group attached to a ring carbon atom at a temperature of from about 100 to about 350 C.

11. A process for producing a resin which comprises heating a phenolic aldehyde dialkylthioacetal at a temperature of from about 100 to about 350 C.

12. A process for producing a resin which comprises heating an orthophenolic aldehyde 5 diaikylthioacetal at a temperature of from about 100 to about 350 C.

13. A resin formed by heating a, hydroxy aromatie aldehyde dialkylthioacetal having a hydroxy group attached to a ring carbon atom at 5 a temperature of from about 100 to about 350 C.

14. A resin formed by heating a phenolic aldehyde diaikylthioacetal at a temperature of from about 100 to about 350 C.

15. A resin formed by heating salicylaldehyde diethylthioacetal at a temperature of from about 100 to about 350 C.

16. A resin formed by heating vanill'm diethylthioacetal at a temperature of from about 100 to about 350 C.

RALPH B. THOMPSON.

* REFERENCES CITED The follov ting references are of record in the tile of this patent:

Arkiv for Kemi, Mineralogi Och Geologi 15 A, No. 8, 1942 (page 5) Stockholm. 

1. A PROCESS FOR PREPARING A RESIN WHICH COMPRISES HEATING THE REACTION PRODUCT FORMED BY REACTION A HYDROXY AROMATIC ALDEHYDE HAVING A HYDROXY GROUP ATTACHED TO A RING CARBON ATOM AND ETHYL MERCAPTAN IN THE PRESENCE OF AN ACIDIC CATALYST, SAID HEATING BEING AT A TEMPERATURE AND FOR A TIME SUFFICIENT TO RESINIFY SAID REACTION PRODUCT. 